Biologically active proteins often have undesirable half-lives when administered as human therapeutics. Their intrinsic half-lives impose administration schedules and dosing regimens that often result in less than optimal therapeutic efficacy, compliance problems and patient inconvenience.
In the manufacture of biologically active proteins for human therapeutics, the extension of the half-life of biologically active proteins has been attempted through physical means (e.g., altered route of administration, nanoparticle encapsulation and liposomal entrapment), chemical modification (e.g., emulsions, pegylation and hyperglycosylation) and genetic modification (e.g., modification of primary protein structure, polymer tags, human serum albumin fusion, incorporation of post-translational modification). See, for example, Lord, et al., Clin. Cancer Res. 7:2085-2090 (2001), and van Der Auwera, et al., Am. J. Hematol. 66:245-251 (2001). However, such approaches have resulted in other problems. Extension of biologically active protein half-life through physical means often introduces increased drug substance complexity with costly and time-consuming additional downstream processes during manufacturing. Chemical modification may alter the biological activity or safety profile of the biologically active protein. Where biologically active proteins are made via recombinant DNA synthesis methodology, the effect of the genetic modification on protein yield and purity in the particular cellular expression systems issues needs to be assessed for its intended use.
Accordingly, there is a need for other approaches for modifying the intrinsic half-life of biologically active proteins.